U.S. patent application number 16/245196 was filed with the patent office on 2019-07-11 for communication device, processing device and method for transmitting buffer status report.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is LG ELECTRONICS INC.. Invention is credited to Geumsan JO, Gyeongcheol LEE, Sunyoung LEE, Seungjune YI.
Application Number | 20190215717 16/245196 |
Document ID | / |
Family ID | 67141185 |
Filed Date | 2019-07-11 |
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United States Patent
Application |
20190215717 |
Kind Code |
A1 |
LEE; Gyeongcheol ; et
al. |
July 11, 2019 |
COMMUNICATION DEVICE, PROCESSING DEVICE AND METHOD FOR TRANSMITTING
BUFFER STATUS REPORT
Abstract
In the present invention, the method, communication device or
processing device determines an amount of uplink (UL) data
available for a logical channel group (LCG); and transmit the
buffer status report including information on the amount of UL data
available for the LCG. In the present invention, the amount of UL
data available for the LCG is selected based on all logical
channels of the LCG except for a logical channel related to a
suspended radio link control (RLC) entity among RLC entities
configured for the communication or processing device.
Inventors: |
LEE; Gyeongcheol; (Seoul,
KR) ; YI; Seungjune; (Seoul, KR) ; LEE;
Sunyoung; (Seoul, KR) ; JO; Geumsan; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
|
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
67141185 |
Appl. No.: |
16/245196 |
Filed: |
January 10, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62615983 |
Jan 11, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 24/10 20130101;
H04W 72/1247 20130101; H04W 80/02 20130101; H04W 72/1284 20130101;
H04W 72/0486 20130101; H04W 28/0278 20130101; H04W 72/14
20130101 |
International
Class: |
H04W 28/02 20060101
H04W028/02; H04W 24/10 20060101 H04W024/10; H04W 72/14 20060101
H04W072/14; H04W 72/12 20060101 H04W072/12 |
Claims
1. A communication device for transmitting a buffer status report
in a wireless communication system, the communication device
comprising: a transceiver, and a processor configured to control
the transceiver, the processor configured to: determine an amount
of uplink (UL) data available for a logical channel group (LCG);
and control the transceiver to transmit the buffer status report
including information on the amount of UL data available for the
LCG, wherein the processor is configured to determine the amount of
UL data available for the LCG based on all logical channels of the
LCG except for a logical channel related to a suspended radio link
control (RLC) entity among RLC entities configured for the
communication device.
2. The communication device according to claim 1, wherein the
logical channel related to the suspended RLC entity comprises a
logical channel related to a suspended radio bearer, a logical
channel related to an RLC entity in which a maximum number of
retransmissions has been reached, a logical channel related to an
RLC entity perform RLC re-establishment, or a logical channel
related to a packet data convergence protocol (PDCP) entity
performing PDCP re-establishment.
3. The communication device according to claim 1, wherein the
processor is configured to: receive an UL grant in response to the
buffer status report; select logical channels related to the UL
grant; allocate resources of the UL grant to the selected logical
channels; and control the transceiver to transmit UL data of the
selected logical channels based on the UL grant, wherein the
processor is configured to select the logical channels related to
the UL grant among logical channels not related to the suspended
RLC entity.
4. The communication device according to claim 3, wherein the
processor is configured to allocate the resources of the UL grant
to the selected logical channels in a predefined order of
priority.
5. The communication device according to claim 3, wherein the
processor is configured to: perform selecting of the logical
channels related to the UL grant and allocating of the resources of
the UL grant at a medium access control (MAC) entity configured in
the processor.
6. A processing device comprising: at least one processor; and at
least one computer memory that is operably connectable to the at
least one processor and that has stored thereon instructions which,
when executed, cause the at least one processor to perform
operations comprising: determining an amount of uplink (UL) data
available for a logical channel group (LCG); and transmitting a
buffer status report including information on the amount of UL data
available for the LCG, wherein the operations determine the amount
of UL data available for the LCG based on all logical channels of
the LCG except for a logical channel related to a suspended radio
link control (RLC) entity among RLC entities configured in the
processing device.
7. The processing device according to claim 6, wherein the logical
channel related to the suspended RLC entity comprises a logical
channel related to a suspended radio bearer, a logical channel
related to an RLC entity in which a maximum number of
retransmissions has been reached, a logical channel related to an
RLC entity perform RLC re-establishment, or a logical channel
related to a packet data convergence protocol (PDCP) entity
performing PDCP re-establishment.
8. The processing device according to claim 6, wherein the
operations further comprises: receiving an UL grant in response to
the buffer status report; selecting logical channels related to the
UL grant; allocating resources of the UL grant to the selected
logical channels; and transmitting UL data of the selected logical
channels based on the UL grant, wherein the operations select the
logical channels related to the UL grant among logical channels not
related to the suspended RLC entity.
9. The processing device according to claim 6, wherein the
operations comprises: allocating the resources of the UL grant to
the selected logical channels in a predefined order of
priority.
10. The processing device according to claim 6, wherein the
operations comprises: performing selecting of the logical channels
related to the UL grant and allocating of the resources of the UL
grant at a medium access control (MAC) entity configured in the
processing device.
11. A method for transmitting, by a communication device, a buffer
status report in a wireless communication system, the method
comprising: determining an amount of uplink (UL) data available for
a logical channel group (LCG); and transmitting the buffer status
report including information on the amount of UL data available for
the LCG, wherein the amount of UL data available for the LCG is
determined based on all logical channels of the LCG except for a
logical channel related to a suspended radio link control (RLC)
entity among RLC entities configured for the communication
device.
12. The method according to claim 11, wherein the logical channel
related to the suspended RLC entity comprises a logical channel
related to a suspended radio bearer, a logical channel related to
an RLC entity in which a maximum number of retransmissions has been
reached, a logical channel related to an RLC entity perform RLC
re-establishment, or a logical channel related to a packet data
convergence protocol (PDCP) entity performing PDCP
re-establishment.
13. The method according to claim 11, further comprising: receiving
an UL grant in response to the buffer status report; selecting
logical channels related to the UL grant; allocating resources of
the UL grant to the selected logical channels; and transmitting UL
data of the selected logical channels based on the UL grant,
wherein the logical channels related to the UL grant are selected
from among logical channels not related to the suspended RLC
entity.
14. The method according to claim 13, wherein the resources of the
UL grant are allocated to the selected logical channels in a
predefined order of priority.
15. The method according to claim 13, wherein selecting the logical
channels related to the UL grant and allocating the resources of
the UL grant are performed at a medium access control (MAC) entity
configured in the communication device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. .sctn. 119(e), this application claims
the benefit of U.S. Provisional Patent Application No. 62/615,983,
filed on Jan. 11, 2018, the contents of which are hereby
incorporated by reference herein in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a wireless communication
system.
BACKGROUND ART
[0003] As an example of a mobile communication system to which the
present disclosure is applicable, a 3rd Generation Partnership
Project Long Term Evolution (hereinafter, referred to as LTE)
communication system is described in brief.
[0004] FIG. 1 is a diagram illustrating an example of a network
structure of an E-UMTS as an exemplary radio communication system.
An Evolved Universal Mobile Telecommunications System (E-UMTS) is
an advanced version of a Universal Mobile Telecommunications System
(UMTS) and basic standardization thereof is currently underway in
the 3GPP. E-UMTS may be generally referred to as a Long Term
Evolution (LTE) system. For details of the technical specifications
of the UMTS and E-UMTS, reference can be made to Release 7 and
Release 8 of "3rd Generation Partnership Project; Technical
Specification Group Radio Access Network".
[0005] Referring to FIG. 1, the E-UMTS includes a User Equipment
(UE), eNode Bs (eNBs), and an Access Gateway (AG) which is located
at an end of the network (E-UTRAN) and connected to an external
network. The eNBs may simultaneously transmit multiple data streams
for a broadcast service, a multicast service, and/or a unicast
service.
[0006] One or more cells may exist per eNB. The cell is set to
operate in one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20
MHz and provides a downlink (DL) or uplink (UL) transmission
service to a plurality of UEs in the bandwidth. Different cells may
be set to provide different bandwidths. The eNB controls data
transmission or reception to and from a plurality of UEs. The eNB
transmits DL scheduling information of DL data to a corresponding
UE so as to inform the UE of a time/frequency domain in which the
DL data is supposed to be transmitted, coding, a data size, and
hybrid automatic repeat and request (HARQ)-related information. In
addition, the eNB transmits UL scheduling information of UL data to
a corresponding UE so as to inform the UE of a time/frequency
domain which may be used by the UE, coding, a data size, and
HARQ-related information. An interface for transmitting user
traffic or control traffic may be used between eNBs. A core network
(CN) may include the AG and a network node or the like for user
registration of UEs. The AG manages the mobility of a UE on a
tracking area (TA) basis. One TA includes a plurality of cells.
SUMMARY
[0007] Introduction of new radio communication technologies has led
to increases in the number of user equipments (UEs) to which a base
station (BS) provides services in a prescribed resource region, and
has also led to increases in the amount of data and control
information that the BS transmits to the UEs. Due to typically
limited resources available to the BS for communication with the
UE(s), new techniques are needed by which the BS utilizes the
limited radio resources to efficiently receive/transmit
uplink/downlink data and/or uplink/downlink control information. In
particular, overcoming delay or latency has become an important
challenge in applications whose performance critically depends on
delay/latency.
[0008] The technical objects that can be achieved through the
present invention are not limited to what has been particularly
described hereinabove and other technical objects not described
herein will be more clearly understood by persons skilled in the
art from the following detailed description.
[0009] In an aspect of the present disclosure, provided herein is a
communication device for transmitting a buffer status report in a
wireless communication system. The communication device comprises a
transceiver, and a processor configured to control the transceiver.
The processor is configured to: determine an amount of uplink (UL)
data available for a logical channel group (LCG); and control the
transceiver to transmit the buffer status report including
information on the amount of UL data available for the LCG. The
processor is configured to determine the amount of UL data
available for the LCG based on all logical channels of the LCG
except for a logical channel related to a suspended radio link
control (RLC) entity among RLC entities configured for the
communication device.
[0010] In another aspect of the present disclosure, provided herein
is a processing device. The processing device comprises at least
one processor; and at least one computer memory that is operably
connectable to the at least one processor and that has stored
thereon instructions which, when executed, cause the at least one
processor to perform operations. The operations comprises:
determining an amount of uplink (UL) data available for a logical
channel group (LCG); and transmitting a buffer status report
including information on the amount of UL data available for the
LCG. The operations comprises determining the amount of UL data
available for the LCG based on all logical channels of the LCG
except for a logical channel related to a suspended radio link
control (RLC) entity among RLC entities configured in the
processing device
[0011] In a further aspect of the present disclosure, provided
herein is a method for transmitting, by a communication device, a
buffer status report in a wireless communication system. The method
comprises: determining an amount of uplink (UL) data available for
a logical channel group (LCG); and transmitting the buffer status
report including information on the amount of UL data available for
the LCG. The amount of UL data available for the LCG is determined
based on all logical channels of the LCG except for a logical
channel related to a suspended radio link control (RLC) entity
among RLC entities configured for the communication device
[0012] In each aspect of the present disclosure, the logical
channel related to the suspended RLC entity may comprise a logical
channel related to a suspended radio bearer, a logical channel
related to an RLC entity in which a maximum number of
retransmissions has been reached, a logical channel related to an
RLC entity perform RLC re-establishment, or a logical channel
related to a packet data convergence protocol (PDCP) entity
performing PDCP re-establishment.
[0013] In each aspect of the present disclosure, the communication
device, the processing device or the method may further perform:
receiving an UL grant may be received in response to the buffer
status report; selecting logical channels related to the UL grant;
allocating resources of the UL grant to the selected logical
channels; and transmitting UL data of the selected logical channels
based on the UL grant. The logical channels related to the UL grant
may be selected from among logical channels not related to the
suspended RLC entity.
[0014] In each aspect of the present disclosure, the resources of
the UL grant may be allocated to the selected logical channels in a
predefined order of priority.
[0015] In each aspect of the present disclosure, selecting the
logical channels related to the UL grant and allocating the
resources of the UL grant may be performed at a medium access
control (MAC) entity.
[0016] The above technical solutions are merely some parts of the
implementations of the present disclosure and various
implementations into which the technical features of the present
disclosure are incorporated can be derived and understood by
persons skilled in the art from the following detailed description
of the present disclosure.
[0017] In some scenarios, implementations of the present disclosure
may provide one or more of the following advantages. In some
scenarios, radio communication signals can be more efficiently
transmitted and/or received. Therefore, overall throughput of a
radio communication system can be improved.
[0018] According to some implementations of the present disclosure,
delay/latency occurring during communication between a user
equipment and a BS may be reduced.
[0019] Also, signals in a new radio access technology system can be
transmitted and/or received more effectively.
[0020] It will be appreciated by persons skilled in the art that
the effects that can be achieved through the present disclosure are
not limited to what has been particularly described hereinabove and
other advantages of the present disclosure will be more clearly
understood from the following detailed description.
BRIEF DESCRIPTION OF DRAWINGS
[0021] The accompanying drawings, which are included to provide a
further understanding of the invention, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention:
[0022] FIG. 1 is a diagram illustrating an example of a network
structure of an evolved universal mobile telecommunication system
(E-UMTS) as an exemplary radio communication system;
[0023] FIG. 2 is a block diagram illustrating an example of an
evolved universal terrestrial radio access network (E-UTRAN);
[0024] FIG. 3 is a block diagram depicting an example of an
architecture of a typical E-UTRAN and a typical EPC;
[0025] FIG. 4 illustrates an example of protocol stacks of the 3GPP
based communication system;
[0026] FIG. 5 illustrates an example of a frame structure in the
3GPP based wireless communication system;
[0027] FIG. 6 illustrates an example of a data flow in the 3GPP NR
system;
[0028] FIG. 7 illustrates a model of an acknowledged mode (AM)
radio link control (RLC) entity which can be used in the
implementation(s) of the present disclosure;
[0029] FIG. 8 illustrates an example of radio protocol architecture
for packet duplication in the 3GPP based communication system;
[0030] FIG. 9 illustrates an implementation example of the present
disclosure; and
[0031] FIG. 10 is a block diagram illustrating examples of
communication devices which can perform method(s) of the present
disclosure.
DETAILED DESCRIPTION
[0032] Although wireless communication technology has been
developed to LTE based on wideband code division multiple access
(WCDMA), the demands and expectations of users and service
providers are on the rise. In addition, considering other radio
access technologies under development, new technological evolution
is required to secure high competitiveness in the future. Decrease
in cost per bit, increase in service availability, flexible use of
frequency bands, a simplified structure, an open interface,
appropriate power consumption of UEs, and the like are
required.
[0033] As more and more communication devices demand larger
communication capacity, there is a need for improved mobile
broadband communication compared to existing RAT. Also, massive
machine type communication (MTC), which provides various services
by connecting many devices and objects, is one of the major issues
to be considered in the next generation communication. In addition,
a communication system design considering a service/UE sensitive to
reliability and latency is being discussed. The introduction of
next-generation RAT, which takes into account such advanced mobile
broadband communication, massive MTC (mMCT), and ultra-reliable and
low latency communication (URLLC), is being discussed.
[0034] Reference will now be made in detail to the exemplary
implementations of the present disclosure, examples of which are
illustrated in the accompanying drawings. The detailed description,
which will be given below with reference to the accompanying
drawings, is intended to explain exemplary implementations of the
present disclosure, rather than to show the only implementations
that can be implemented according to the disclosure. The following
detailed description includes specific details in order to provide
a thorough understanding of the present disclosure. However, it
will be apparent to those skilled in the art that the present
disclosure may be practiced without such specific details.
[0035] The following techniques, apparatuses, and systems may be
applied to a variety of wireless multiple access systems. Examples
of the multiple access systems include a code division multiple
access (CDMA) system, a frequency division multiple access (FDMA)
system, a time division multiple access (TDMA) system, an
orthogonal frequency division multiple access (OFDMA) system, a
single carrier frequency division multiple access (SC-FDMA) system,
and a multicarrier frequency division multiple access (MC-FDMA)
system. CDMA may be embodied through radio technology such as
universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be
embodied through radio technology such as global system for mobile
communications (GSM), general packet radio service (GPRS), or
enhanced data rates for GSM evolution (EDGE). OFDMA may be embodied
through radio technology such as institute of electrical and
electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),
IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is a part of a
universal mobile telecommunications system (UMTS). 3rd generation
partnership project (3GPP) long term evolution (LTE) is a part of
evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL
and SC-FDMA in UL. LTE-advanced (LTE-A) is an evolved version of
3GPP LTE. For convenience of description, implementations of the
present disclosure are described in regards to a 3GPP based
wireless communication system. However, the technical features of
the present disclosure are not limited thereto. For example,
although the following detailed description is given based on a
mobile communication system corresponding to a 3GPP based system,
aspects of the present disclosure that are not limited to 3GPP
based system are applicable to other mobile communication
systems.
[0036] For example, the present disclosure is applicable to
contention based communication such as Wi-Fi as well as
non-contention based communication as in the 3GPP based system in
which a BS allocates a DL/UL time/frequency resource to a UE and
the UE receives a DL signal and transmits a UL signal according to
resource allocation of the BS. In a non-contention based
communication scheme, an access point (AP) or a control node for
controlling the AP allocates a resource for communication between
the UE and the AP, whereas, in a contention based communication
scheme, a communication resource is occupied through contention
between UEs which desire to access the AP. The contention based
communication scheme will now be described in brief. One type of
the contention based communication scheme is carrier sense multiple
access (CSMA). CSMA refers to a probabilistic media access control
(MAC) protocol for confirming, before a node or a communication
device transmits traffic on a shared transmission medium (also
called a shared channel) such as a frequency band, that there is no
other traffic on the same shared transmission medium. In CSMA, a
transmitting device determines whether another transmission is
being performed before attempting to transmit traffic to a
receiving device. In other words, the transmitting device attempts
to detect presence of a carrier from another transmitting device
before attempting to perform transmission. Upon sensing the
carrier, the transmitting device waits for another transmission
device which is performing transmission to finish transmission,
before performing transmission thereof. Consequently, CSMA can be a
communication scheme based on the principle of "sense before
transmit" or "listen before talk". A scheme for avoiding collision
between transmitting devices in the contention based communication
system using CSMA includes carrier sense multiple access with
collision detection (CSMA/CD) and/or carrier sense multiple access
with collision avoidance (CSMA/CA). CSMA/CD is a collision
detection scheme in a wired local area network (LAN) environment.
In CSMA/CD, a personal computer (PC) or a server which desires to
perform communication in an Ethernet environment first confirms
whether communication occurs on a network and, if another device
carries data on the network, the PC or the server waits and then
transmits data. That is, when two or more users (e.g. PCs, UEs,
etc.) simultaneously transmit data, collision occurs between
simultaneous transmission and CSMA/CD is a scheme for flexibly
transmitting data by monitoring collision. A transmitting device
using CSMA/CD adjusts data transmission thereof by sensing data
transmission performed by another device using a specific rule.
CSMA/CA is a MAC protocol specified in IEEE 802.11 standards. A
wireless LAN (WLAN) system conforming to IEEE 802.11 standards does
not use CSMA/CD which has been used in IEEE 802.3 standards and
uses CA, i.e. a collision avoidance scheme. Transmission devices
always sense carrier of a network and, if the network is empty, the
transmission devices wait for determined time according to
locations thereof registered in a list and then transmit data.
Various methods are used to determine priority of the transmission
devices in the list and to reconfigure priority. In a system
according to some versions of IEEE 802.11 standards, collision may
occur and, in this case, a collision sensing procedure is
performed. A transmission device using CSMA/CA avoids collision
between data transmission thereof and data transmission of another
transmission device using a specific rule.
[0037] For terms and technologies which are not specifically
described among the terms of and technologies employed in the
present disclosure, the wireless communication standard documents
published before the present disclosure may be referenced. For
example, the following documents may be referenced.
[0038] 3GPP LTE [0039] 3GPP TS 36.211: Physical channels and
modulation [0040] 3GPP TS 36.212: Multiplexing and channel coding
[0041] 3GPP TS 36.213: Physical layer procedures [0042] 3GPP TS
36.214: Physical layer; Measurements [0043] 3GPP TS 36.300: Overall
description [0044] 3GPP TS 36.304: User Equipment (UE) procedures
in idle mode [0045] 3GPP TS 36.314: Layer 2--Measurements [0046]
3GPP TS 36.321: Medium Access Control (MAC) protocol [0047] 3GPP TS
36.322: Radio Link Control (RLC) protocol [0048] 3GPP TS 36.323:
Packet Data Convergence Protocol (PDCP) [0049] 3GPP TS 36.331:
Radio Resource Control (RRC) protocol
[0050] 3GPP NR [0051] 3GPP TS 38.211: Physical channels and
modulation [0052] 3GPP TS 38.212: Multiplexing and channel coding
[0053] 3GPP TS 38.213: Physical layer procedures for control [0054]
3GPP TS 38.214: Physical layer procedures for data [0055] 3GPP TS
38.215: Physical layer measurements [0056] 3GPP TS 38.300: Overall
description [0057] 3GPP TS 38.304: User Equipment (UE) procedures
in idle mode and in RRC inactive state [0058] 3GPP TS 38.321:
Medium Access Control (MAC) protocol [0059] 3GPP TS 38.322: Radio
Link Control (RLC) protocol [0060] 3GPP TS 38.323: Packet Data
Convergence Protocol (PDCP) [0061] 3GPP TS 38.331: Radio Resource
Control (RRC) protocol [0062] 3GPP TS 37.324: Service Data
Adaptation Protocol (SDAP) [0063] 3GPP TS 37.340:
Multi-connectivity; Overall description
[0064] In the present disclosure, a user equipment (UE) may be a
fixed or mobile device. Examples of the UE include various devices
that transmit and receive user data and/or various kinds of control
information to and from a base station (BS). The UE may be referred
to as a terminal equipment (TE), a mobile station (MS), a mobile
terminal (MT), a user terminal (UT), a subscriber station (SS), a
wireless device, a personal digital assistant (PDA), a wireless
modem, a handheld device, etc. In addition, in the present
disclosure, a BS generally refers to a fixed station that performs
communication with a UE and/or another BS, and exchanges various
kinds of data and control information with the UE and another BS.
The BS may be referred to as an advanced base station (ABS), a
node-B (NB), an evolved node-B (eNB), a base transceiver system
(BTS), an access point (AP), a processing server (PS), etc.
Especially, a BS of the UMTS is referred to as a NB, a BS of the
EPC/LTE is referred to as an eNB, and a BS of the new radio (NR)
system is referred to as a gNB.
[0065] In the present disclosure, a node refers to a fixed point
capable of transmitting/receiving a radio signal through
communication with a UE. Various types of BSs may be used as nodes
irrespective of the terms thereof. For example, a BS, a node B
(NB), an enode B (eNB), a pico-cell eNB (PeNB), a home eNB (HeNB),
a relay, a repeater, etc. may be a node. In addition, the node may
not be a BS. For example, the node may be a radio remote head (RRH)
or a radio remote unit (RRU). The RRH or RRU generally has a lower
power level than a power level of a BS. Since the RRH or RRU
(hereinafter, RRH/RRU) is generally connected to the BS through a
dedicated line such as an optical cable, cooperative communication
between RRH/RRU and the BS can be smoothly performed in comparison
with cooperative communication between BSs connected by a radio
line. At least one antenna is installed per node. The antenna may
include a physical antenna or an antenna port or a virtual
antenna.
[0066] In the present disclosure, the term "cell" may refer to a
geographic area to which one or more nodes provide a communication
system, or refer to radio resources. A "cell" of a geographic area
may be understood as coverage within which a node can provide
service using a carrier and a "cell" as radio resources (e.g.
time-frequency resources) is associated with bandwidth (BW) which
is a frequency range configured by the carrier. The "cell"
associated with the radio resources is defined by a combination of
downlink resources and uplink resources, for example, a combination
of a downlink (DL) component carrier (CC) and a uplink (UL) CC. The
cell may be configured by downlink resources only, or may be
configured by downlink resources and uplink resources. Since DL
coverage, which is a range within which the node is capable of
transmitting a valid signal, and UL coverage, which is a range
within which the node is capable of receiving the valid signal from
the UE, depends upon a carrier carrying the signal, the coverage of
the node may be associated with coverage of the "cell" of radio
resources used by the node. Accordingly, the term "cell" may be
used to represent service coverage of the node sometimes, radio
resources at other times, or a range that signals using the radio
resources can reach with valid strength at other times.
[0067] In carrier aggregation (CA), two or more CCs are aggregated.
A UE may simultaneously receive or transmit on one or multiple CCs
depending on its capabilities. CA is supported for both contiguous
and non-contiguous CCs. When CA is configured the UE only has one
radio resource control (RRC) connection with the network. At RRC
connection establishment/re-establishment/handover, one serving
cell provides the non-access stratum (NAS) mobility information,
and at RRC connection re-establishment/handover, one serving cell
provides the security input. This cell is referred to as the
Primary Cell (PCell). The PCell is a cell, operating on the primary
frequency, in which the UE either performs the initial connection
establishment procedure or initiates the connection
re-establishment procedure. Depending on UE capabilities, Secondary
Cells (SCells) can be configured to form together with the PCell a
set of serving cells. An SCell is a cell providing additional radio
resources on top of Special Cell. The configured set of serving
cells for a UE therefore always consists of one PCell and one or
more SCells. For dual connectivity operation, the term Special Cell
(SpCell) refers to the PCell of the master cell group (MCG) or the
PSCell of the secondary cell group (SCG). An SpCell supports PUCCH
transmission and contention-based random access, and is always
activated. The MCG is a group of serving cells associated with a
master node, comprising of the SpCell (PCell) and optionally one or
more SCells. The SCG is the subset of serving cells associated with
a secondary node, comprising of the PSCell and zero or more SCells,
for a UE configured with dual connectivity (DC). For a UE in
RRC_CONNECTED not configured with CA/DC there is only one serving
cell comprising of the PCell. For a UE in RRC_CONNECTED configured
with CA/DC the term "serving cells" is used to denote the set of
cells comprising of the SpCell(s) and all SCells. In DC, two MAC
entities are configured in a UE: one for the MCG and one for the
SCG.
[0068] In the present disclosure, "PDCCH" may refer to a PDCCH, an
EPDCCH (in subframes when configured), a MTC PDCCH (MPDCCH), for an
RN with R-PDCCH configured and not suspended, to the R-PDCCH or,
for NB-IoT to the narrowband PDCCH (NPDCCH).
[0069] In the present disclosure, monitoring a channel refers to
attempting to decode the channel. For example, monitoring a PDCCH
refers to attempting to decode PDCCH(s) (or PDCCH candidates).
[0070] In the present disclosure, for dual connectivity (DC)
operation, the term "special Cell" refers to the PCell of the
master cell group (MCG) or the PSCell of the secondary cell group
(SCG), and otherwise the term Special Cell refers to the PCell. The
MCG is a group of serving cells associated with a master BS which
terminates at least S1-MME, and the SCG is a group of serving cells
associated with a secondary BS that is providing additional radio
resources for the UE but is not the master BS. The SCG includes a
primary SCell (PSCell) and optionally one or more SCells. In dual
connectivity, two MAC entities are configured in the UE: one for
the MCG and one for the SCG. Each MAC entity is configured by RRC
with a serving cell supporting PUCCH transmission and contention
based Random Access. In this specification, the term SpCell refers
to such cell, whereas the term SCell refers to other serving cells.
The term SpCell either refers to the PCell of the MCG or the PSCell
of the SCG depending on if the MAC entity is associated to the MCG
or the SCG, respectively.
[0071] In the present disclosure, "C-RNTI" refers to a cell RNTI,
"SI-RNTI" refers to a system information RNTI, "P-RNTI" refers to a
paging RNTI, "RA-RNTI" refers to a random access RNTI, "SC-RNTI"
refers to a single cell RNTI", "SL-RNTI" refers to a sidelink RNTI,
"SPS C-RNTI" refers to a semi-persistent scheduling C-RNTI, and
"CS-RNTI" refers to a configured scheduling RNTI.
[0072] FIG. 2 is a block diagram illustrating an example of an
evolved universal terrestrial radio access network (E-UTRAN). The
E-UMTS may be also referred to as an LTE system. The communication
network is widely deployed to provide a variety of communication
services such as voice (VoIP) through IMS and packet data.
[0073] As illustrated in FIG. 2, the E-UMTS network includes an
evolved UMTS terrestrial radio access network (E-UTRAN), an Evolved
Packet Core (EPC) and one or more user equipment. The E-UTRAN may
include one or more evolved NodeB (eNodeB) 20, and a plurality of
user equipments (UE) 10 may be located in one cell. One or more
E-UTRAN mobility management entity (MME)/system architecture
evolution (SAE) gateways 30 may be positioned at the end of the
network and connected to an external network.
[0074] As used herein, "downlink" refers to communication from BS
20 to UE 10, and "uplink" refers to communication from the UE to a
BS.
[0075] FIG. 3 is a block diagram depicting an example of an
architecture of a typical E-UTRAN and a typical EPC.
[0076] As illustrated in FIG. 3, an eNB 20 provides end points of a
user plane and a control plane to the UE 10. MME/SAE gateway 30
provides an end point of a session and mobility management function
for UE 10. The eNB and MME/SAE gateway may be connected via an S
interface.
[0077] The eNB 20 is generally a fixed station that communicates
with a UE 10, and may also be referred to as a base station (BS) or
an access point. One eNB 20 may be deployed per cell. An interface
for transmitting user traffic or control traffic may be used
between eNBs 20.
[0078] The MME provides various functions including NAS signaling
to eNBs 20, NAS signaling security, access stratum (AS) Security
control, Inter CN node signaling for mobility between 3GPP access
networks, Idle mode UE Reachability (including control and
execution of paging retransmission), Tracking Area list management
(for UE in idle and active mode), PDN GW and Serving GW selection,
MME selection for handovers with MME change, SGSN selection for
handovers to 2G or 3G 3GPP access networks, roaming,
authentication, bearer management functions including dedicated
bearer establishment, support for PWS (which includes ETWS and
CMAS) message transmission. The SAE gateway host provides assorted
functions including Per-user based packet filtering (by e.g. deep
packet inspection), Lawful Interception, UE IP address allocation,
Transport level packet marking in the downlink, UL and DL service
level charging, gating and rate enforcement, DL rate enforcement
based on APN-AMBR. For clarity MME/SAE gateway 30 will be referred
to herein simply as a "gateway," but it is understood that this
entity includes both an MME and an SAE gateway.
[0079] A plurality of nodes may be connected between eNB 20 and
gateway 30 via the S1 interface. The eNBs 20 may be connected to
each other via an X2 interface and neighboring eNBs may have a
meshed network structure that has the X2 interface.
[0080] As illustrated, eNB 20 may perform functions of selection
for gateway 30, routing toward the gateway during a Radio Resource
Control (RRC) activation, scheduling and transmitting of paging
messages, scheduling and transmitting of Broadcast Channel (BCCH)
information, dynamic allocation of resources to UEs 10 in both
uplink and downlink, configuration and provisioning of eNB
measurements, radio bearer control, radio admission control (RAC),
and connection mobility control in LTE_ACTIVE state. In the EPC,
and as noted above, gateway 30 may perform functions of paging
origination, LTE-IDLE state management, ciphering of the user
plane, System Architecture Evolution (SAE) bearer control, and
ciphering and integrity protection of Non-Access Stratum (NAS)
signaling.
[0081] The EPC includes a mobility management entity (MME), a
serving-gateway (S-GW), and a packet data network-gateway (PDN-GW).
The MME has information about connections and capabilities of UEs,
mainly for use in managing the mobility of the UEs. The S-GW is a
gateway having the E-UTRAN as an end point, and the PDN-GW is a
gateway having a packet data network (PDN) as an end point.
[0082] A fully mobile and connected society is expected in the near
future, which will be characterized by a tremendous amount of
growth in connectivity, traffic volume and a much broader range of
usage scenarios. Some typical trends include explosive growth of
data traffic, great increase of connected devices and continuous
emergence of new services. Besides the market requirements, the
mobile communication society itself also requires a sustainable
development of the eco-system, which produces the needs to further
improve system efficiencies, such as spectrum efficiency, energy
efficiency, operational efficiency and cost efficiency. To meet the
above ever-increasing requirements from market and mobile
communication society, next generation access technologies are
expected to emerge in the near future.
[0083] Building upon its success of IMT-2000 (3G) and IMT-Advanced
(4G), 3GPP has been devoting its effort to IMT-2020 (5G)
development since September 2015. 5G New Radio (NR) is expected to
expand and support diverse use case scenarios and applications that
will continue beyond the current IMT-Advanced standard, for
instance, enhanced Mobile Broadband (eMBB), Ultra Reliable Low
Latency Communication (URLLC) and massive Machine Type
Communication (mMTC). eMBB is targeting high data rate mobile
broadband services, such as seamless data access both indoors and
outdoors, and augmented reality (AR)/virtual reality (VR)
applications; URLLC is defined for applications that have stringent
latency and reliability requirements, such as vehicular
communications that can enable autonomous driving and control
network in industrial plants; mMTC is the basis for connectivity in
IoT, which allows for infrastructure management, environmental
monitoring, and healthcare applications.
[0084] FIG. 4 illustrates an example of protocol stacks in a 3GPP
based wireless communication system.
[0085] In particular, FIG. 4(a) illustrates an example of a radio
interface user plane protocol stack between a UE and a base station
(BS) and FIG. 4(b) illustrates an example of a radio interface
control plane protocol stack between a UE and a BS. The control
plane refers to a path through which control messages used to
manage call by a UE and a network are transported. The user plane
refers to a path through which data generated in an application
layer, for example, voice data or Internet packet data are
transported. Referring to FIG. 4(a), the user plane protocol stack
may be divided into a first layer (Layer 1) (i.e., a physical (PHY)
layer) and a second layer (Layer 2). Referring to FIG. 4(b), the
control plane protocol stack may be divided into Layer 1 (i.e., a
PHY layer), Layer 2, Layer 3 (e.g., a radio resource control (RRC)
layer), and a non-access stratum (NAS) layer. Layer 1, Layer 2 and
Layer 3 are referred to as an access stratum (AS).
[0086] In the 3GPP LTE system, the layer 2 is split into the
following sublayers: Medium Access Control (MAC), Radio Link
Control (RLC), and Packet Data Convergence Protocol (PDCP). In the
3GPP New Radio (NR) system, the layer 2 is split into the following
sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC
sublayer transport channels, the MAC sublayer offers to the RLC
sublayer logical channels, the RLC sublayer offers to the PDCP
sublayer RLC channels, the PDCP sublayer offers to the SDAP
sublayer radio bearers. The SDAP sublayer offers to 5G Core Network
QoS flows.
[0087] In the 3GPP NR system, the main services and functions of
SDAP include: mapping between a QoS flow and a data radio bearer;
marking QoS flow ID (QFI) in both DL and UL packets. A single
protocol entity of SDAP is configured for each individual PDU
session.
[0088] In the 3GPP NR system, the main services and functions of
the RRC sublayer include: broadcast of system information related
to AS and NAS; paging initiated by 5GC or NG-RAN; establishment,
maintenance and release of an RRC connection between the UE and
NG-RAN; security functions including key management; establishment,
configuration, maintenance and release of Signalling Radio Bearers
(SRBs) and Data Radio Bearers (DRBs); mobility functions
(including: handover and context transfer; UE cell selection and
reselection and control of cell selection and reselection;
Inter-RAT mobility); QoS management functions; UE measurement
reporting and control of the reporting; detection of and recovery
from radio link failure; NAS message transfer to/from NAS from/to
UE.
[0089] In the 3GPP NR system, the main services and functions of
the PDCP sublayer for the user plane include: sequence numbering;
header compression and decompression: ROHC only; transfer of user
data; reordering and duplicate detection; in-order delivery; PDCP
PDU routing (in case of split bearers); retransmission of PDCP
SDUs; ciphering, deciphering and integrity protection; PDCP SDU
discard; PDCP re-establishment and data recovery for RLC AM; PDCP
status reporting for RLC AM; duplication of PDCP PDUs and duplicate
discard indication to lower layers. The main services and functions
of the PDCP sublayer for the control plane include: sequence
numbering; ciphering, deciphering and integrity protection;
transfer of control plane data; reordering and duplicate detection;
in-order delivery; duplication of PDCP PDUs and duplicate discard
indication to lower layers.
[0090] In the 3GPP NR system, the RLC sublayer supports three
transmission modes: Transparent Mode (TM); Unacknowledged Mode
(UM); and Acknowledged Mode (AM). The RLC configuration is per
logical channel with no dependency on numerologies and/or
transmission durations. In the 3GPP NR system, the main services
and functions of the RLC sublayer depend on the transmission mode
and include: Transfer of upper layer PDUs; sequence numbering
independent of the one in PDCP (UM and AM); error correction
through ARQ (AM only); segmentation (AM and UM) and re-segmentation
(AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate
detection (AM only); RLC SDU discard (AM and UM); RLC
re-establishment; protocol error detection (AM only).
[0091] In the 3GPP NR system, the main services and functions of
the MAC sublayer include: mapping between logical channels and
transport channels; multiplexing/demultiplexing of MAC SDUs
belonging to one or different logical channels into/from transport
blocks (TB) delivered to/from the physical layer on transport
channels; scheduling information reporting; error correction
through HARQ (one HARQ entity per cell in case of carrier
aggregation (CA)); priority handling between UEs by means of
dynamic scheduling; priority handling between logical channels of
one UE by means of logical channel prioritization; padding. A
single MAC entity may support multiple numerologies, transmission
timings and cells. Mapping restrictions in logical channel
prioritization control which numerology(ies), cell(s), and
transmission timing(s) a logical channel can use. Different kinds
of data transfer services are offered by MAC. To accommodate
different kinds of data transfer services, multiple types of
logical channels are defined i.e. each supporting transfer of a
particular type of information. Each logical channel type is
defined by what type of information is transferred. Logical
channels are classified into two groups: Control Channels and
Traffic Channels. Control channels are used for the transfer of
control plane information only, and traffic channels are used for
the transfer of user plane information only. Broadcast Control
Channel (BCCH) is a downlink logical channel for broadcasting
system control information, paging Control Channel (PCCH) is a
downlink logical channel that transfers paging information, system
information change notifications and indications of ongoing PWS
broadcasts, Common Control Channel (CCCH) is a logical channel for
transmitting control information between UEs and network and used
for UEs having no RRC connection with the network, and Dedicated
Control Channel (DCCH) is a point-to-point bi-directional logical
channel that transmits dedicated control information between a UE
and the network and used by UEs having an RRC connection. Dedicated
Traffic Channel (DTCH) is a point-to-point logical channel,
dedicated to one UE, for the transfer of user information. A DTCH
can exist in both uplink and downlink. In Downlink, the following
connections between logical channels and transport channels exist:
BCCH can be mapped to BCH; BCCH can be mapped to downlink shared
channel (DL-SCH); PCCH can be mapped to PCH; CCCH can be mapped to
DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to
DL-SCH. In Uplink, the following connections between logical
channels and transport channels exist: CCCH can be mapped to uplink
shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can
be mapped to UL-SCH.
[0092] FIG. 5 illustrates an example of a frame structure in the
3GPP based wireless communication system.
[0093] The frame structure illustrated in FIG. 5 is purely
exemplary and the number of subframes, the number of slots, and/or
the number of symbols in a frame may be variously changed. In the
3GPP based wireless communication system, an OFDM numerology (e.g.,
subcarrier spacing (SCS), transmission time interval (TTI)
duration) may be differently configured between a plurality of
cells aggregated for one UE. For example, if a UE is configured
with different SCSs for cells aggregated for the cell, an (absolute
time) duration of a time resource (e.g. a subframe, a slot, or a
TTI) including the same number of symbols may be different among
the aggregated cells. Herein, symbols may include OFDM symbols (or
CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier
transform-spread-OFDM (DFT-s-OFDM) symbols).
[0094] Referring to FIG. 5, downlink and uplink transmissions are
organized into frames. Each frame has T.sub.f=10 ms duration. Each
frame is divided into two half-frames, where each of the
half-frames has 5 ms duration. Each half-frame consists of 5
subframes, where the duration T.sub.sf per subframe is 1 ms. Each
subframe is divided into slots and the number of slots in a
subframe depends on a subcarrier spacing. Each slot includes 14 or
12 OFDM symbols based on a cyclic prefix (CP). In a normal CP, each
slot includes 14 OFDM symbols and, in an extended CP, each slot
includes 12 OFDM symbols. The numerology is based on exponentially
scalable subcarrier spacing .DELTA.f=2.sup.u*15 kHz. The following
table shows the number of OFDM symbols per slot, the number of
slots per frame, and the number of slots per for the normal CP,
according to the subcarrier spacing .DELTA.f=2.sup.u*15 kHz.
TABLE-US-00001 TABLE 1 u N.sup.slot.sub.symb N.sup.frame,
u.sub.slot N.sup.subframe, u.sub.slot 0 14 10 1 1 14 20 2 2 14 40 4
3 14 80 8 4 14 160 16
[0095] The following table shows the number of OFDM symbols per
slot, the number of slots per frame, and the number of slots per
for the extended CP, according to the subcarrier spacing
.DELTA.f=2.sup.u*15 kHz.
TABLE-US-00002 TABLE 2 u N.sup.slot.sub.symb N.sup.frame,
u.sub.slot N.sup.subframe, u.sub.slot 2 12 40 4
[0096] A slot includes plural symbols (e.g., 14 or 12 symbols) in
the time domain. For each numerology (e.g. subcarrier spacing) and
carrier, a resource grid of N.sup.size,u.sub.grid,x N.sup.RB.sub.sc
subcarriers and N.sup.subframe,u.sub.symb OFDM symbols is defined,
starting at common resource block (CRB) N.sup.start,u.sub.grid
indicated by higher-layer signaling (e.g. radio resource control
(RRC) signaling), where N.sup.size,u.sub.grid,x is the number of
resource blocks (RBs) in the resource grid and the subscript x is
DL for downlink and UL for uplink. N.sup.RB.sub.sc is the number of
subcarriers per RB. In the 3GPP based wireless communication
system, N.sup.RB.sub.sc is 12 generally. There is one resource grid
for a given antenna port p, subcarrier spacing configuration u, and
transmission direction (DL or UL). The carrier bandwidth
N.sup.size,u.sub.grid for subcarrier spacing configuration u is
given by the higher-layer parameter (e.g. RRC parameter). Each
element in the resource grid for the antenna port p and the
subcarrier spacing configuration u is referred to as a resource
element (RE) and one complex symbol may be mapped to each RE. Each
RE in the resource grid is uniquely identified by an index k in the
frequency domain and an index l representing a symbol location
relative to a reference point in the time domain. In the 3GPP based
wireless communication system, an RB is defined by 12 consecutive
subcarriers in the frequency domain.
[0097] In the 3GPP NR system, RBs are classified into CRBs and
physical resource blocks (PRBs). CRBs are numbered from 0 and
upwards in the frequency domain for subcarrier spacing
configuration u. The center of subcarrier 0 of CRB 0 for subcarrier
spacing configuration u coincides with `point A` which serves as a
common reference point for resource block grids. In the 3GPP NR
system, PRBs are defined within a bandwidth part (BWP) and numbered
from 0 to N.sup.size.sub.BWP,i-1, where i is the number of the
bandwidth part. The relation between the physical resource block
n.sub.PRB in the bandwidth part i and the common resource block
n.sub.CRB is as follows: n.sub.PRB=n.sub.CRB+N.sup.size.sub.BWP,i,
where N.sup.size.sub.BWP,i is the common resource block where
bandwidth part starts relative to CRB 0. The BWP includes a
plurality of consecutive RBs. A carrier may include a maximum of N
(e.g., 5) BWPs. A UE may be configured with one or more BWPs on a
given component carrier. Only one BWP among BWPs configured to the
UE can active at a time. The active BWP defines the UE's operating
bandwidth within the cell's operating bandwidth.
[0098] FIG. 6 illustrates an example of a data flow in the 3GPP NR
system. In FIG. 6, "H" denotes headers and subheaders.
[0099] The MAC PDU is transmitted/received using radio resources
through the PHY layer to/from an external device. The MAC PDU
arrives to the PHY layer in the form of a transport block. In the
PHY layer, the uplink transport channels UL-SCH and RACH are mapped
to their physical channels PUSCH and PRACH, respectively, and the
downlink transport channels DL-SCH, BCH and PCH are mapped to
PDSCH, PBCH and PDSCH, respectively. In the PHY layer, uplink
control information (UCI) is mapped to PUCCH, and downlink control
information (DCI) is mapped to PDCCH. A MAC PDU related to UL-SCH
is transmitted by a UE via a PUSCH based on an UL grant, and a MAC
PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a
DL assignment.
[0100] Functions of the PDCP sublayer are performed by PDCP
entities. Several PDCP entities may be defined for a UE. Each PDCP
entity is carrying the data of one radio bearer. A PDCP entity is
associated either to the control plane or the user plane depending
on which radio bearer it is carrying data for. Each RB (except for
SRBO) is associated with one PDCP entity. Each PDCP entity is
associated with one, two, or four RLC entities depending on the RB
characteristic (e.g. uni-directional/bi-directional or
split/non-split) or RLC mode. For non-split bearers, each PDCP
entity is associated with one UM RLC entity, two UM RLC entities
(one for each direction), or one AM RLC entity. For split bearers,
each PDCP entity is associated with two UM RLC entities (for same
direction), four UM RLC entities (two for each direction), or two
AM RLC entities (for same direction).
[0101] When upper layers (e.g. RRC) request a PDCP entity
establishment for a radio bearer, the UE establishes a PDCP entity
for the radio bearer; sets state variables of the PDCP entity to
initial values; and follows the data transfer procedure.
[0102] When upper layers (e.g. RRC) request a PDCP entity
re-establishment, the transmitting PDCP entity: for UM DRBs and AM
DRBs, resets the header compression protocol for uplink and start
with an IR state in U-mode if drb-ContinueROHC is not configured in
RRC; for UM DRBs and SRBs, sets TX_NEXT to the initial value; for
SRBs, discard all stored PDCP SDUs and PDCP PDUs; applies the
ciphering algorithm and key provided by upper layers during the
PDCP entity re-establishment procedure; applies the integrity
protection algorithm and key provided by upper layers during the
PDCP entity re-establishment procedure; for UM DRBs, for each PDCP
SDU already associated with a PDCP SN but for which a corresponding
PDU has not previously been submitted to lower layers, considers
the PDCP SDUs as received from upper layer and performs
transmission of the PDCP SDUs in ascending order of the COUNT value
associated to the PDCP SDU prior to the PDCP re-establishment
without restarting the discardTimer; for AM DRBs, from the first
PDCP SDU for which the successful delivery of the corresponding
PDCP Data PDU has not been confirmed by lower layers, performs
retransmission or transmission of all the PDCP SDUs already
associated with PDCP SNs in ascending order of the COUNT values
associated to the PDCP SDU prior to the PDCP entity
re-establishment. After performing the PDCP entity
re-establishment, the UE follows the data transfer procedure.
[0103] Functions of the RLC sublayer are performed by RLC entities.
For an RLC entity configured at a BS, there is a peer RLC entity
configured at the UE and vice versa. When upper layers (e.g. RRC)
request an RLC entity establishment, the UE establishes an RLC
entity, sets the state variable of the RLC entity to initial
values, and follows the data transfer procedure. When upper layers
(e.g. RRC) request an RLC entity re-establishment, the UE discards
all RLC SDUs, RLC SDU segments, and RLC PDUs, if any; stops and
resets all timers; and resets all state variables to their initial
values. When upper layers (e.g. RRC) request an RLC entity release,
the UE discards all RLC SDUs, RLC SDU segments, and RLC PDUs, if
any; and releases the RLC entity.
[0104] An RLC entity receives/delivers RLC SDUs from/to upper layer
and sends/receives RLC PDUs to/from its peer RLC entity via lower
layers. An RLC entity can be configured to perform data transfer in
one of the following three modes: Transparent Mode (TM),
Unacknowledged Mode (UM) or Acknowledged Mode (AM). Consequently,
an RLC entity is categorized as a TM RLC entity, an UM RLC entity
or an AM RLC entity depending on the mode of data transfer that the
RLC entity is configured to provide. A TM RLC entity is configured
either as a transmitting TM RLC entity or a receiving TM RLC
entity. The transmitting TM RLC entity receives RLC SDUs from upper
layer and sends RLC PDUs to its peer receiving TM RLC entity via
lower layers. The receiving TM RLC entity delivers RLC SDUs to
upper layer and receives RLC PDUs from its peer transmitting TM RLC
entity via lower layers. An UM RLC entity is configured either as a
transmitting UM RLC entity or a receiving UM RLC entity. The
transmitting UM RLC entity receives RLC SDUs from upper layer and
sends RLC PDUs to its peer receiving UM RLC entity via lower
layers. The receiving UM RLC entity delivers RLC SDUs to upper
layer and receives RLC PDUs from its peer transmitting UM RLC
entity via lower layers. An AM RLC entity consists of a
transmitting side and a receiving side. The transmitting side of an
AM RLC entity receives RLC SDUs from upper layer and sends RLC PDUs
to its peer AM RLC entity via lower layers. The receiving side of
an AM RLC entity delivers RLC SDUs to upper layer and receives RLC
PDUs from its peer AM RLC entity via lower layers.
[0105] In the implementations of the present disclosure, the
following services are expected by RLC from lower layer (i.e. MAC):
data transfer; and notification of a transmission opportunity
together with the total size of the RLC PDU(s) to be transmitted in
the transmission opportunity.
[0106] FIG. 7 illustrates a model of an acknowledged mode (AM)
radio link control (RLC) entity which can be used in the
implementation(s) of the present disclosure.
[0107] In the 3GPP NR system, RLC SDUs of variable sizes which are
byte aligned (i.e. multiple of 8 bits) are supported for all RLC
entity type (TM, UM and AM RLC entity), which is similar in the
3GPP LTE system. In the 3GPP LTE system, however, each RLC SDU is
used to construct an RLC PDU without waiting for notification from
the lower layer (i.e., by MAC) of a transmission opportunity. In
the case of UM and AM RLC entities, an RLC SDU may be segmented and
transported using two or more RLC PDUs based on the notification(s)
from the lower layer. RLC PDUs are submitted to lower layer only
when a transmission opportunity has been notified by lower layer
(i.e. by MAC). In other words, in the 3GPP NR system, the RLC
entity is allowed to construct RLC data PDUs in advance even
without notification of a transmission opportunity by the lower
layer, i.e., pre-construction of RLC data PDU is allowed. When and
how many RLC data PDUs are pre-constructed is left up to UE
implementation.
[0108] Referring to FIG. 9, an AM RLC entity can be configured to
deliver/receive RLC PDUs through the following logical channels:
DL/UL DCCH or DL/UL DTCH. An AM RLC entity delivers/receives the
following RLC data PDUs: AMD PDU. An AMD PDU contains either one
complete RLC SDU or one RLC SDU segment. An AM RLC entity
delivers/receives a STATUS PDU which is an RLC control PDU.
[0109] In the implementation(s) of the present disclosure, the
transmitting side of an AM RLC entity generates AMD PDU(s) for each
RLC SDU. When notified of a transmission opportunity by the lower
layer, the transmitting AM RLC entity segments the RLC SDUs, if
needed, so that the corresponding AMD PDUs, with RLC headers
updated as needed, fit within the total size of RLC PDU(s)
indicated by lower layer.
[0110] The transmitting side of an AM RLC entity supports
retransmission of RLC SDUs or RLC SDU segments (ARQ): [0111] if the
RLC SDU or RLC SDU segment to be retransmitted (including the RLC
header) does not fit within the total size of RLC PDU(s) indicated
by lower layer at the particular transmission opportunity notified
by lower layer, the AM RLC entity can segment the RLC SDU or
re-segment the RLC SDU segments into RLC SDU segments, [0112] the
number of re-segmentation is not limited.
[0113] When the transmitting side of an AM RLC entity forms AMD
PDUs from RLC SDUs or RLC SDU segments, it includes relevant RLC
headers in the AMD PDU.
[0114] In the implementation(s) of the present disclosure, an AMD
PDU consists of a Data field and an AMD PDU header. An AM RLC
entity may configured by RRC to use either a 12 bit SN or a 18 bit
SN. An AMD PDU header contains a P field and a SN.
[0115] An AMD PDU consists of a Data field and an AMD PDU header.
The P field is included in the AMD PDU header, and indicates
whether or not the transmitting side of an LTE AM RLC entity
requests a STATUS report from its peer LTE AM RLC entity. The
interpretation of the P field is provided in the following
table
TABLE-US-00003 TABLE 3 Value Description 0 Status report not
requested 1 Status report is requested
[0116] In the implementation(s) of the present disclosure, data
transfer procedures between the transmitting side of an RLC entity
and the receiving side of an RLC entity are as follows.
[0117] The transmitting side of an AM RLC entity prioritizes
transmission of RLC control PDUs over AMD PDUs. The transmitting
side of an AM RLC entity prioritizes transmission of AMD PDUs
containing previously transmitted RLC SDUs or RLC SDU segments over
transmission of AMD PDUs containing not previously transmitted RLC
SDUs or RLC SDU segments.
[0118] The transmitting side of an AM RLC entity maintains a
transmitting window according to the state variable TX_Next_Ack as
follows: [0119] a SN falls within the transmitting window if
TX_Next_Ack<=SN<TX_Next_Ack+AM_Window_Size; [0120] a SN falls
outside of the transmitting window otherwise. TX_Next_Ack is the
acknowledgement state variable maintained in the transmitting side
of each AM RLC entity, and holds the value of the SN of the next
RLC SDU for which a positive acknowledgment is to be received
in-sequence, and it serves as the lower edge of the transmitting
window. It is initially set to 0, and is updated whenever the AM
RLC entity receives a positive acknowledgment for an RLC SDU with
SN=TX_Next_Ack. AM_Window_Size is a constant used by both the
transmitting side and the receiving side of each AM RLC entity.
AM_Window_Size=2048 when a 12 bit SN is used, AM_Window_Size=131072
when an 18 bit SN is used.
[0121] The transmitting side of an AM RLC entity does not submit to
lower layer (i.e. MAC) any AMD PDU whose SN falls outside of the
transmitting window. In other words, any AMD PDU whose SN falls
outside of the transmitting window is not transmitted in a
corresponding transmission opportunity.
[0122] For each RLC SDU received from the upper layer (e.g. PDCP),
the AM RLC entity associates a SN with the RLC SDU equal to TX_Next
and constructs an AMD PDU by setting the SN of the AMD PDU to
TX_Next, and increments TX_Next by one. TX_Next is a state variable
maintained in the transmitting side of each AM RLC entity and holds
the value of the SN to be assigned for the next newly generated AMD
PDU. TX_Next is initially set to 0, and is updated whenever the AM
RLC entity constructs an AMD PDU with SN=TX_Next which contains an
RLC SDU or the last segment of an RLC SDU.
[0123] When submitting an AMD PDU that contains a segment of an RLC
SDU, to lower layer, the transmitting side of an AM RLC entity sets
the SN of the AMD PDU to the SN of the corresponding RLC SDU.
[0124] The transmitting side of an AM RLC entity can receive a
positive acknowledgement (confirmation of successful reception by
its peer AM RLC entity) for an RLC SDU by a STATUS PDU from its
peer AM RLC entity.
[0125] When receiving a positive acknowledgement for an RLC SDU
with SN=x, the transmitting side of an AM RLC entity sends an
indication to the upper layers of successful delivery of the RLC
SDU; and sets TX_Next_Ack equal to the SN of the RLC SDU with the
smallest SN, whose SN falls within the range
TX_Next_Ack<=SN<=TX_Next and for which a positive
acknowledgments has not been received yet.
[0126] The transmitting side of an AM RLC entity can receive a
negative acknowledgement (notification of reception failure by its
peer AM RLC entity) for an RLC SDU or an RLC SDU segment by a
STATUS PDU from its peer AM RLC entity.
[0127] When receiving a negative acknowledgement for an RLC SDU or
an RLC SDU segment by a STATUS PDU from its peer AM RLC entity, the
transmitting side of the AM RLC entity may consider the RLC SDU or
the RLC SDU segment, for which a negative acknowledgement was
received, for retransmission if the SN of the corresponding RLC SDU
falls within the range TX_Next_Ack<=SN<TX_Next.
[0128] When an RLC SDU or an RLC SDU segment is considered for
retransmission, the transmitting side of the AM RLC entity: [0129]
sets the RETX_COUNT associated with the RLC SDU to zero if the RLC
SDU or RLC SDU segment is considered for retransmission for the
first time; [0130] increments the RETX_COUNT if it (the RLC SDU or
the RLC SDU segment that is considered for retransmission) is not
pending for retransmission already and the RETX_COUNT associated
with the RLC SDU has not been incremented due to another negative
acknowledgment in the same STATUS PDU; [0131] indicate to upper
layers (e.g. RRC) that the maximum number of retransmissions has
been reached if RETX_COUNT=maxRetxThreshold. RETX_COUNT is a
counter maintained in the transmitting side of each AM RLC entity
and counts the number of retransmissions of an RLC SDU or RLC SDU
segment. There is one RETX_COUNT counter maintained per RLC SDU.
maxRetxThreshold is a parameter configured by RRC, and used by the
transmitting side of each AM RLC entity to limit the number of
retransmissions corresponding to an RLC SDU, including its
segments. If the transmitting side of an AM RLC entity is a UE, the
UE is configured with maxRetxThreshold by receiving
maxRetxThreshold via RRC signaling from a network (e.g. BS).
[0132] When retransmitting an RLC SDU or an RLC SDU segment, the
transmitting side of an AM RLC entity: [0133] segments the RLC SDU
or the RLC SDU segment if needed; [0134] forms a new AMD PDU which
will fit within the total size of AMD PDU(s) indicated by lower
layer at the particular transmission opportunity; and [0135]
submits the new AMD PDU to lower layer.
[0136] When forming a new AMD PDU, the transmitting side of an AM
RLC entity: [0137] maps only the original RLC SDU or RLC SDU
segment to the Data field of the new AMD PDU; and [0138] modifies
the header of the new AMD PDU.
[0139] An AM RLC entity can poll its peer AM RLC entity in order to
trigger STATUS reporting at the peer AM RLC entity. The
transmitting side of an AM RLC entity can poll its peer AM RLC
entity by submitting an RLC data PDU including a poll to MAC layer
for transmission. In the present disclosure, an RLC data PDU
including a poll means an RLC data PDU with the poll bit set to
"1". In other words, in the present disclosure, including a poll in
an RLC PDU refers to including the value "1" in the P field
included in the RLC PDU, and an RLC PDU including a poll means an
RLC PDU whose P field includes the value "1".
[0140] When an AMD PDU is received from lower layer (MAC), where
the AMD PDU contains byte segment numbers y to z of an RLC SDU with
SN=x, the receiving side of an AM RLC entity: [0141] if x falls
outside of the receiving window; or [0142] if byte segment numbers
y to z of the RLC SDU with SN=x have been received before: [0143]
discard the received AMD PDU. [0144] else: [0145] place the
received AMD PDU in the reception buffer; [0146] if some byte
segments of the RLC SDU contained in the AMD PDU have been received
before: [0147] discard the duplicate byte segments.
[0148] An AM RLC entity sends STATUS PDUs to its peer AM RLC entity
in order to provide positive and/or negative acknowledgements of
RLC SDUs (or portions of them). Triggers to initiate STATUS
reporting include: [0149] Polling from its peer AM RLC entity:
[0150] When an AMD PDU with SN=x and the P field set to "1" is
received from lower layer (MAC), the receiving side of an AM RLC
entity: [0151] if the AMD PDU is to be discarded as described
above; or [0152] if x<RX_Highest_Status or
x>=RX_Next+AM_Window_Size: [0153] trigger a STATUS report.
[0154] else: [0155] delay triggering the STATUS report until
x<RX_Highest_Status or x>=RX_Next+AM_Window_Size. [0156]
Detection of reception failure of an AMD PDU: [0157] The receiving
side of an AM RLC entity shall trigger a STATUS report when
t-Reassembly expires.
[0158] The receiving side of each AM RLC entity maintains state
variables RX_Highest_Status and RX_Next. RX_Highest_Status is the
maximum STATUS transmit state variable which holds the highest
possible value of the SN which can be indicated by "ACK_SN" when a
STATUS PDU needs to be constructed. RX_Highest_Status is initially
set to 0. RX_Next is the receive state variable which holds the
value of the SN following the last in-sequence completely received
RLC SDU, and it serves as the lower edge of the receiving window.
RX_Next is initially set to 0, and is updated whenever the AM RLC
entity receives an RLC SDU with SN=RX_Next.
[0159] The expiry of t-Reassembly triggers both RX_Highest_Status
to be updated and a STATUS report to be triggered, but the STATUS
report shall be triggered after RX_Highest_Status is updated.
t-Reassembly is a timer configured by RRC, and used by the
receiving side of an AM RLC entity and receiving UM RLC entity in
order to detect loss of RLC PDUs at lower layer. If t-Reassembly is
running, t-Reassembly is not started additionally, i.e. only one
t-Reassembly per RLC entity is running at a given time.
[0160] When STATUS reporting has been triggered, the receiving side
of an AM RLC entity: [0161] if t-StatusProhibit is not running:
[0162] at the first transmission opportunity indicated by lower
layer, constructs a STATUS PDU and submit it to lower layer. [0163]
else: [0164] at the first transmission opportunity indicated by
lower layer after t-StatusProhibit expires, constructs a single
STATUS PDU even if status reporting was triggered several times
while t-StatusProhibit was running and submit it to lower
layer.
[0165] t-StatusProhibit is a timer configured by RRC, and used by
the receiving side of an AM RLC entity in order to prohibit
transmission of a STATUS PDU. When a STATUS PDU has been submitted
to lower layer, the receiving side of an AM RLC entity starts
t-StatusProhibit.
[0166] In addition, if a STATUS PDU has been triggered and
t-StatusProhibit is not running or has expired, the UE shall
estimate the size of the STATUS PDU that will be transmitted in the
next transmission opportunity, and consider this as part of RLC
data volume.
[0167] FIG. 8 illustrates an example of radio protocol architecture
for packet duplication in the 3GPP based communication system.
[0168] In carrier aggregation (CA) of the legacy 3GPP LTE system,
when the transmitting side of an AM RLC entity reaches the maximum
number of retransmission, the transmitting side of an AM RLC entity
indicates to upper layers (RRC) that the maximum number of
retransmissions has been reached and then the RRC layer performs
RRC re-establishment procedure. All RLC entities would be
re-established by RRC re-establishment procedure.
[0169] In the 3GPP based communication system, PDCP packet
duplication is newly introduced and can be configured with CA.
Hereinafter, this is called CA duplication. When duplication is
configured for a radio bearer by RRC, at least one secondary RLC
entity and at least one secondary logical channel are added to the
radio bearer to handle the duplicated PDCP PDUs. Referring to FIG.
8, duplication at PDCP therefore consists in submitting the same
PDCP PDUs twice: once to the primary RLC entity and a second time
to the secondary RLC entity. With two independent transmission
paths, packet duplication therefore increases reliability and
reduces latency and is especially beneficial for ultra-reliable
low-latency communication (URLLC) services. When duplication is
activated, the original PDCP PDU and the corresponding duplicate
shall not be transmitted on the same carrier. In CA duplication,
the two different logical channels can either belong to the same
MAC entity (CA).
[0170] For the 3GPP based communication, it has been recently
agreed that, in CA duplication, when the transmitting side of an AM
RLC entity, which is configured on an SCell, reaches the maximum
number of retransmission, the RRC does not perform RRC connection
re-establishment and reports the failure to the BS. As RRC does not
perform RRC re-establishment, MAC is not reset. This situation is
different from a radio bearer suspension at RRC connection
re-establishment procedure, where the MAC entity is reset.
[0171] In this condition, even though the transmitting side of an
AM RLC entity reaches the maximum number of retransmissions, all
remaining RLC entities except for the RLC entity reaching maximum
number of retransmissions can keep submitting RLC PDUs to lower
layer (i.e., MAC) upon receiving notification of a transmission
opportunity by lower layer. In other words, only the RLC entity
reaching the maximum number of retransmissions, which is configured
on an SCell, is suspended and cannot transmit a data until RLC
re-establishment is performed.
[0172] However, the transmitting side of an AM RLC entity indicates
to upper layers only that the maximum number of retransmissions has
been reached. Therefore, the MAC entity does not know whether an
RLC entity is suspended or not. As the MAC entity is not reset, it
performs normal operation related to transmission.
[0173] The MAC entity supports functions related to transmission.
The MAC functions related to transmission comprise priority
handling between logical channels of one UE by means of logical
channel prioritization (LCP), and scheduling information reporting
such as buffer status reporting. If the MAC entity does not know
whether an RLC entity is suspended or not, the MAC entity would
include the logical channel, which is associated with a suspended
RLC entity, into LCP procedure for an UL grant. Eventually even if
the suspended RLC entity cannot transmit data, the MAC entity would
give an unnecessary transmission opportunity to the suspended RLC
entity after LCP. Another problem can occur in the buffer status
report (BSR) procedure. Actually the suspended RLC entity should
not be included into data volume calculation because available data
into the suspended RLC entity cannot be transmitted. This means
that if the logical channel associated with the suspended RLC
entity is included into the BSR procedure, MAC may report very
large buffer status to the BS unnecessarily. This is serious
problem and can deteriorate performance of the whole system.
[0174] Therefore, a new indication informing a lower layer (i.e.
MAC) that the maximum number of retransmissions has been reached
should be introduced, and the MAC entity should apply the
indication to the MAC procedure to resolve these problems.
[0175] In the implementations of the present disclosure, when a MAC
entity performs a MAC procedure for transmission, the MAC entity
handles all logical channels except for a logical channel
associated with a suspended RLC entity during the MAC
procedure.
[0176] The implementations of the present disclosure can be applied
to any type of UE, e.g., machine type communication (MTC) UE,
narrowband internet of things (NB-IoT) UE, normal UE.
[0177] In the implementations of the present disclosure, a logical
channel associated with a suspended RLC entity can be indicated by
upper layers (i.e., RLC, PDCP, or RRC).
[0178] In the present disclosure, a logical channel associated with
a suspended RLC entity may mean: [0179] a logical channel
associated with a suspended radio bearer (RB), [0180] a logical
channel associated with an RLC entity in which the maximum number
of retransmissions has been reached, [0181] a logical channel
associated with an RLC entity performing RLC re-establishment,
and/or [0182] a logical channel associated with a PDCP entity
performing PDCP re-establishment.
[0183] The suspended radio bearer may mean a radio bearer which
cannot transport uplink data while other radio bearers can
transport uplink data. If an RRC connection is suspended, all RBs
are suspended. Unlike the normal RRC connection suspension, in the
implementations of the present disclosure, only a specific RB may
be suspended while transmission/reception on the other RBs is
performed normally.
[0184] In other words, in the present disclosure, a suspended RLC
entity may mean: [0185] an RLC entity associated with a suspended
radio bearer (RB), [0186] an RLC entity in which the maximum number
of retransmissions has been reached, [0187] an RLC entity
performing RLC re-establishment, and/or [0188] an RLC entity
associated with a PDCP entity performing PDCP re-establishment.
[0189] In the present disclosure, the MAC procedure for
transmission includes logical channel prioritization (LCP) and/or
buffer status reporting.
[0190] In the implementations of the present disclosure, an uplink
grant is dynamically allocated via grant is either received
dynamically on the PDCCH, in a Random Access Response, or
configured semi-persistently by RRC. A UE monitors the PDCCH(s) in
order to find possible grants for uplink transmission when its
downlink reception is enabled (activity governed by discontinuous
reception (DRX) when configured). In addition, with Configured
Grants, the BS can allocate uplink resources for the initial HARQ
transmissions to UEs. Two types of configured uplink grants are
defined: Type 1 and Type 2. With Configured Grant Type 1, RRC
directly provides the configured uplink grant (including the
periodicity). For example, a UE is provided with at least
information on time domain resource, information on frequency
domain resource, and modulation coding scheme index, via RRC
signaling from a BS when the configured grant type 1 is configured.
With Configured Grant Type 2, RRC defines the periodicity of the
configured uplink grant while PDCCH addressed to Configured
Scheduling RNTI (CS-RNTI) can either signal and activate the
configured uplink grant, or deactivate it; i.e. a PDCCH addressed
to CS-RNTI indicates that the uplink grant can be implicitly reused
according to the periodicity defined by RRC, until deactivated.
[0191] When the MAC entity receives indication of a logical channel
associated with a suspended RLC entity from upper layers, the MAC
entity considers the indicated logical channel is associated with a
suspended RLC entity during the MAC procedure for transmission as
described below.
[0192] The MAC multiplexes MAC control elements (CEs) and MAC SDUs
in a MAC PDU based on the Logical Channel Prioritization procedure.
In the present disclosure, the Logical Channel Prioritization
procedure is applied whenever a new transmission is performed. RRC
(of the BS) controls the scheduling of uplink data by signalling
for each logical channel per MAC entity to a UE: [0193] priority
where an increasing priority value indicates a lower priority
level; [0194] prioritisedBitRate which sets the Prioritized Bit
Rate (PBR); [0195] bucketSizeDuration which sets the Bucket Size
Duration (BSD).
[0196] RRC (of the BS) additionally controls the LCP procedure by
configuring mapping restrictions for each logical channel by
signalling the following mapping restrictions to a UE: [0197]
lcp-allowedSCS which sets the allowed Subcarrier Spacing(s) for
transmission; [0198] lcp-maxPUSCH-Duration which sets the maximum
PUSCH duration allowed for transmission; [0199]
lcp-configuredGrantTypelAllowed which sets whether a Configured
Grant Type 1 can be used for transmission; [0200]
lcp-allowedServingCells which sets the allowed cell(s) for
transmission.
[0201] The MAC entity maintains a variable Bj for each logical
channel j. Bj is initialized to zero when the related logical
channel is established, and incremented before every instance of
the LCP procedure by the product PBR*T, where PBR is Prioritized
Bit Rate of logical channel j and T is the time elapsed since Bj
was last updated. The exact moment(s) when the UE updates Bj
between LCP procedures is up to UE implementation, as long as Bj is
up to date at the time when a grant is processed by LCP. However,
the value of Bj can never exceed the bucket size and if the value
of Bj is larger than the bucket size of logical channel j, it shall
be set to the bucket size. The bucket size of a logical channel is
equal to PBR*BSD.
[0202] If the MAC entity is requested to simultaneously transmit
multiple MAC PDUs, or if the MAC entity receives the multiple UL
grants within one or more coinciding PDCCH occasions (i.e. on
different serving cells), it is up to UE implementation in which
order the grants are processed.
[0203] *Selection of Logical Channels
[0204] In an implementation of the present disclosure, the MAC
entity may exclude a logical channel associated with a suspended
RLC entity when selecting logical channel(s) for a UL grant. For
example, when a new transmission is performed, the MAC entity may
select logical channels for each UL grant that satisfy all the
following conditions: [0205] the set of allowed Subcarrier Spacing
index values in lcp-allowedSCS, if configured, includes the
Subcarrier Spacing index associated to the UL grant; and [0206]
lcp-maxPUSCH-Duration, if configured, is larger than or equal to
the PUSCH transmission duration associated to the UL grant; and
[0207] lcp-configuredGrantTypelAllowed, if configured, is set to
TRUE in case the UL grant is a Configured Grant Type 1; and [0208]
lcp-allowedServingCells, if configured, includes the Cell
information associated to the UL grant; and [0209] a logical
channel is not associated with a suspended RLC entity.
[0210] The Subcarrier Spacing index, PUSCH transmission duration
and Cell information are included in Uplink transmission
information received from lower layers for the corresponding
scheduled uplink transmission.
[0211] *Allocation of Resources
[0212] When a new transmission is performed, the MAC entity
allocates resources to the logical channels as follows: [0213]
logical channels selected for the UL grant with Bj>0 are
allocated resources in a decreasing priority order. If the PBR of a
logical channel is set to "infinity", the MAC entity shall allocate
resources for all the data that is available for transmission on
the logical channel before meeting the PBR of the lower priority
logical channel(s); [0214] decrement Bj by the total size of MAC
SDUs served to logical channel j above, the value of Bj can be
negative; [0215] if any resources remain, all the logical channels
selected through Section of logical channel are served in a strict
decreasing priority order (regardless of the value of Bj) until
either the data for that logical channel or the UL grant is
exhausted, whichever comes first. Logical channels configured with
equal priority should be served equally.
[0216] The UE also follows the rules below during the scheduling
procedures above: [0217] the UE should not segment an RLC SDU (or
partially transmitted SDU or retransmitted RLC PDU) if the whole
SDU (or partially transmitted SDU or retransmitted RLC PDU) fits
into the remaining resources of the associated MAC entity; [0218]
if the UE segments an RLC SDU from the logical channel, it shall
maximize the size of the segment to fill the grant of the
associated MAC entity as much as possible; [0219] the UE should
maximise the transmission of data; [0220] if the MAC entity is
given an UL grant size that is equal to or larger than 8 bytes
while having data available for transmission, the MAC entity shall
not transmit only padding BSR and/or padding.
[0221] The MAC entity does not generate a MAC PDU for the hybrid
automatic repeat request (HARQ) entity if the following conditions
are satisfied: [0222] the MAC entity is configured with
skipUplinkTxDynamic and the grant indicated to the HARQ entity was
addressed to a C-RNTI, or the grant indicated to the HARQ entity is
a configured uplink grant; and [0223] the MAC PDU includes zero MAC
SDUs; and [0224] the MAC PDU includes only the periodic BSR and
there is no data available for any logical channel group (LCG), or
the MAC PDU includes only the padding BSR.
[0225] RRC (of the BS) can configure the MAC entity with
skipUplinkTxDynamic by signalling skipUplinkTxDynami to the UE. If
skipUplinkTxDynami is set to true, the UE skips UL transmissions
for an uplink grant other than a configured grant if no data is
available for transmission in the UE buffer.
[0226] Logical channels are prioritised in accordance with the
following order (highest priority listed first): [0227] MAC control
element (CE) for C-RNTI or data from UL-CCCH; [0228] MAC CE for
semi-persistent scheduling (SPS) confirmation; [0229] MAC CE for
BSR, with exception of BSR included for padding; [0230] MAC CE for
single entry power headroom report (PHR) or multiple entry PHR;
[0231] data from any Logical Channel, except data from UL-CCCH;
[0232] MAC CE for BSR included for padding.
[0233] The Buffer Status reporting (BSR) procedure is used to
provide the serving BS with information about UL data volume in the
MAC entity. RRC (of the BS) configures the following parameters to
control the BSR of the UE: [0234] periodicBSR-Timer; [0235]
retxBSR-Timer; [0236] logicalChannelSR-Delay; [0237]
logicalChannelSR-DelayTimer; [0238] logicalChannelGroup.
[0239] Each logical channel may be allocated to an LCG using the
logicalChannelGroup. The maximum number of LCGs may be eight.
[0240] The MAC entity determines the amount of UL data available
for a logical channel according to the data volume calculation
procedure in RLC and PDCP.
[0241] In the data volume calculation procedure of RLC, for the
purpose of MAC buffer status reporting, the UE considers the
following as RLC data volume: [0242] RLC SDUs and RLC SDU segments
that have not yet been included in an RLC data PDU; [0243] RLC data
PDUs that are pending for initial transmission; [0244] RLC data
PDUs that are pending for retransmission (RLC AM).
[0245] In the data volume calculation procedure of PDCP, for the
purpose of MAC buffer status reporting, the transmitting PDCP
entity considers the following as PDCP data volume: [0246] the PDCP
SDUs for which no PDCP Data PDUs have been constructed; [0247] the
PDCP Data PDUs that have not been submitted to lower layers; [0248]
the PDCP Control PDUs; [0249] for AM DRBs, the PDCP SDUs to be
retransmitted; [0250] for AM DRBs, the PDCP Data PDUs to be
retransmitted.
[0251] If the transmitting PDCP entity is associated with two RLC
entities, when indicating the PDCP data volume to a MAC entity for
BSR triggering and Buffer Size calculation, the transmitting PDCP
entity: [0252] if the PDCP duplication is activated: [0253]
indicates the PDCP data volume to the MAC entity associated with
the primary RLC entity; [0254] indicates the PDCP data volume
excluding the PDCP Control PDU to the MAC entity associated with
the secondary RLC entity; [0255] else: [0256] if the two associated
RLC entities belong to the different Cell Groups; and [0257] if the
total amount of PDCP data volume and RLC data volume pending for
initial transmission (as specified in TS 38.322 [5]) in the two
associated RLC entities is equal to or larger than
ul-DataSplitThreshold: [0258] indicates the PDCP data volume to
both the MAC entity associated with the primary RLC entity and the
MAC entity associated with the secondary RLC entity; [0259] else:
[0260] indicate the PDCP data volume to the MAC entity associated
with the primary RLC entity; [0261] indicate the PDCP data volume
as 0 to the MAC entity associated with the secondary RLC entity.
ul-DataSplitThreshold is configured by RRC.
[0262] In an implementation of the present disclosure, the MAC
entity may exclude a logical channel associated with a suspended
RLC entity when calculating data volume for an LCG. For example,
when the MAC entity calculates buffer size level of an LCG, for
each logical channel in the LCG, the MAC entity: [0263] checks
whether a logical channel is associated with a suspended RLC
entity; [0264] does not calculate the amount of UL data available
for a logical channel, which includes data volume calculation of
the RLC layer and data volume calculation of the PDCP layer, if the
logical channel is associated with a suspended RLC entity; [0265]
calculates the amount of UL data available for a logical channel,
which includes data volume calculation of the RLC entity associated
with the MAC entity and data volume calculation of the PDCP entity
associated with the MAC entity, if the logical channel is not
associated with a suspended RLC entity; [0266] add the calculated
amount of UL data available for the logical channel to the buffer
size of the LCG.
[0267] When the MAC entity calculates buffer size level of an LCG,
the MAC entity combines the amount of UL data available for all
logical channels except for a logical channel associated with a
suspended RLC entity in the LCG.
[0268] A BSR is triggered if any of the following events occur:
[0269] the MAC entity has new UL data available for a logical
channel which belongs to an LCG; and either [0270] the new UL data
belongs to a logical channel with higher priority than the priority
of any logical channel containing available UL data which belong to
any LCG; or [0271] none of the logical channels which belong to an
LCG contains any available UL data. [0272] in which case the BSR is
referred below to as `Regular BSR`; [0273] UL resources are
allocated and number of padding bits is equal to or larger than the
size of the Buffer Status Report MAC CE plus its subheader, in
which case the BSR is referred below to as `Padding BSR`; [0274]
retxBSR-Timer expires, and at least one of the logical channels
which belong to an LCG contains UL data, in which case the BSR is
referred below to as `Regular BSR`; [0275] periodicBSR-Timer
expires, in which case the BSR is referred below to as `Periodic
BSR`.
[0276] For Regular BSR, the MAC entity:
[0277] 1> if the BSR is triggered for a logical channel for
which logicalChannelSR-Delay is configured by upper layers:
[0278] 2>> starts or restarts the
logicalChannelSR-DelayTimer.
[0279] 1> else:
[0280] 2>> if running, stops the
logicalChannelSR-DelayTimer.
[0281] For Regular and Periodic BSR, the MAC entity shall:
[0282] 1> if more than one LCG has data available for
transmission when the BSR is to be transmitted:
[0283] 2>> reports Long BSR for all LCGs which have data
available for transmission.
[0284] 1> else:
[0285] 2>> reports Short BSR.
[0286] For Padding BSR:
[0287] 1> if the number of padding bits is equal to or larger
than the size of the Short BSR plus its subheader but smaller than
the size of the Long BSR plus its subheader:
[0288] 2>> if more than one LCG has data available for
transmission when the BSR is to be transmitted:
[0289] 3>>> if the number of padding bits is equal to the
size of the Short BSR plus its subheader:
[0290] 4>>>> reports Short Truncated BSR of the LCG
with the highest priority logical channel with data available for
transmission.
[0291] 3>>> else:
[0292] 4>>>> reports Long Truncated BSR of the LCG(s)
with the logical channels having data available for transmission
following a decreasing order of priority, and in case of equal
priority, in increasing order of LCGID.
[0293] 2>> else:
[0294] 3>>> reports Short BSR;
[0295] 1> else if the number of padding bits is equal to or
larger than the size of the Long BSR plus its subheader:
[0296] 2>> reports Long BSR for all LCGs which have data
available for transmission.
[0297] The MAC entity:
[0298] 1> if the Buffer Status reporting procedure determines
that at least one BSR has been triggered and not cancelled:
[0299] 2>> if UL-SCH resources are available for a new
immediate transmission:
[0300] 3>>> instruct the Multiplexing and Assembly
procedure to generate the BSR MAC CE(s);
[0301] 3>>> start or restart periodicBSR-Timer except when
all the generated BSRs are long or short Truncated BSRs;
[0302] 3>>> start or restart retxBSR-Timer.
[0303] 2>> else if a Regular BSR has been triggered and
logicalChannelSR-DelayTimer is not running:
[0304] 3>>> if an uplink grant is not a configured grant;
or
[0305] 3>>> if the Regular BSR was not triggered for a
logical channel for which logical channel SR masking
(logicalChannelSR-Mask) is setup by upper layers:
[0306] 4>>>> trigger a Scheduling Request.
[0307] A MAC PDU contains at most one BSR MAC CE, even when
multiple events have triggered a BSR by the time. The Regular BSR
and the Periodic BSR have precedence over the padding BSR.
[0308] The MAC entity shall restart retxBSR-Timer upon reception of
a grant for transmission of new data on any uplink shared channel
(UL-SCH).
[0309] All triggered BSRs may be cancelled when the UL grant(s) can
accommodate all pending data available for transmission but is not
sufficient to additionally accommodate the BSR MAC control element
plus its subheader. All triggered BSRs shall be cancelled when a
BSR is included in a MAC PDU for transmission.
[0310] The MAC entity shall transmit at most one BSR in one MAC
PDU. Padding BSR shall not be included when the MAC PDU contains a
Regular or Periodic BSR.
[0311] FIG. 9 illustrates an implementation example of the present
disclosure. In FIG. 9, it is assumed that logical channel (LCH) 2
is associated with a suspended RLC entity as indicated by upper
layers. It is also assumed that the calculated amount of UL data
available for each logical channel is 100 bytes, which are combined
results of data volume calculation of a PDCP entity and data volume
calculation of a RLC entity. It is also assumed that all logical
channels are included in the logical channel group (LCG) 1.
[0312] When the MAC entity receives a UL grant from the BS, the MAC
entity performs Selection of logical channels and Allocation of
resources.
[0313] In Selection of logical channels, the MAC entity selects the
LCH 1 for the UL grant; does not select the LCH 2 for the UL grant
because LCH 2 is associated with a suspended RLC entity; selects
the LCH 3 for the UL grant; and selects the LCH 4 for the UL
grant.
[0314] In Allocation of resources, the MAC entity allocate the UL
grant to LCH 1, 3, and 4 except for LCH 2,
[0315] When the MAC entity calculates buffer size level of the LCG
1 during the BSR procedure, the MAC entity: [0316] include the
amount of UL data available for the LCH 1, to the buffer size of
the LCG (the current buffer size level of the LCG is 100 bytes);
[0317] not include the amount of UL data available for the LCH 2
because LCH 2 is associated with a suspended RLC entity (the
current buffer size level of the LCG is 100 bytes); [0318] include
the amount of UL data available for the LCH 3, to the buffer size
of the LCG (the current buffer size level of the LCG is 200 bytes);
[0319] include the amount of UL data available for the LCH 4, to
the buffer size of the LCG (the current buffer size level of the
LCG is 300 bytes).
[0320] If the logical channel of the suspended RLC entity can be
selected in the LCP procedure, radio resources of an UL grant would
be wrongly allocated to the logical channel that cannot transmit
any data. It would also cause waste of the UL grant or require
another round of LCP procedure. Considering this, in the
implementations of the present disclosure, the logical channel of
the suspended RLC entity is excluded when the MAC entity performs
the LCP procedure.
[0321] If the PDCP data volume and RLC data volume of the suspended
RLC entity are included in the buffer size calculation, the BSR
reports larger amount data than actually can be transmitted. It
would cause waste of UL grant. Considering this, in the
implementations of the present disclosure, the PDCP/RLC data volume
of the suspended RLC entity should be excluded from the buffer size
calculation.
[0322] FIG. 10 is a block diagram illustrating examples of
communication devices which can perform method(s) of the present
disclosure.
[0323] In FIG. 10, one of the communication device 1100 and the
communication device 1200 may be a user equipment (UE) and the
other one mat be a base station (BS). Alternatively, one of the
communication device 1100 and the communication device 1200 may be
a UE and the other one may be another UE. Alternatively, one of the
communication device 1100 and the communication device 1200 may be
a network node and the other one may be another network node. In
the present disclosure, the network node may be a base station
(BS). In some scenarios, the network node may be a core network
device (e.g. a network device with a mobility management function,
a network device with a session management function, and etc.).
[0324] In some scenarios of the present disclosure, either one of
the communication devices 1100, 1200, or each of the communication
devices 1100, 1200 may be wireless communication device(s)
configured to transmit/receive radio signals to/from an external
device, or equipped with a wireless communication module to
transmit/receive radio signals to/from an external device. The
wireless communication module may be a transceiver 1113 or 1213.
The wireless communication device is not limited to a UE or a BS,
and the wireless communication device may be any suitable mobile
computing device that is configured to implement one or more
implementations of the present disclosure, such as a vehicular
communication system or device, a wearable device, a laptop, a
smartphone, and so on. A communication device which is mentioned as
a UE or BS in the present disclosure may be replaced by any
wireless communication device such as a vehicular communication
system or device, a wearable device, a laptop, a smartphone, and so
on.
[0325] In the present disclosure, communication devices 1100, 1200
include processors 1111, 1211 and memories 1112, 1212. The
communication devices 1100 may further include transceivers 1113,
1213 or configured to be operatively connected to transceivers
1113, 1213.
[0326] The processor 1111, 1211 implements functions, procedures,
and/or methods disclosed in the present disclosure. One or more
protocols may be implemented by the processor 1111, 1211. For
example, the processor 1111, 1211 may implement one or more layers
(e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP).
The processor 1111, 1211 may generate protocol data units (PDUs)
and/or service data units (SDUs) according to functions,
procedures, and/or methods disclosed in the present disclosure. The
processor 1111, 1211 may generate messages or information according
to functions, procedures, and/or methods disclosed in the present
disclosure. The processor 1111, 1211 may generate signals (e.g.
baseband signals) containing PDUs, SDUs, messages or information
according to functions, procedures, and/or methods disclosed in the
present disclosure and provide the signals to the transceiver 1113
and/or 1213 connected thereto. The processor 1111, 1211 may receive
signals (e.g. baseband signals) from the transceiver 1113, 1213
connected thereto and obtain PDUs, SDUs, messages or information
according to functions, procedures, and/or methods disclosed in the
present disclosure.
[0327] The processor 1111, 1211 may be referred to as controller,
microcontroller, microprocessor, or microcomputer. The processor
1111, 1211 may be implemented by hardware, firmware, software, or a
combination thereof. In a hardware configuration, application
specific integrated circuits (ASICs), digital signal processors
(DSPs), digital signal processing devices (DSPDs), programmable
logic devices (PLDs), or field programmable gate arrays (FPGAs) may
be included in the processor 1111, 1211. The present disclosure may
be implemented using firmware or software, and the firmware or
software may be configured to include modules, procedures,
functions, etc. performing the functions or operations of the
present disclosure. Firmware or software configured to perform the
present disclosure may be included in the processor 1111, 1211 or
stored in the memory 1112, 1212 so as to be driven by the processor
1111, 1211.
[0328] The memory 1112, 1212 is connected to the processor of the
network node and stores various types of PDUs, SDUs, messages,
information and/or instructions. The memory 1112, 1212 may be
arranged inside or outside the processor 1111, 1211, or may be
connected to the processor 1111, 1211 through various techniques,
such as wired or wireless connections.
[0329] The transceiver 1113, 1213 is connected to the processor
1111, 1211, and may be controlled by the processor 1111, 1211 to
transmit and/or receive a signal to/from an external device. The
processor 1111, 1211 may control the transceiver 1113, 1213 to
initiate communication and to transmit or receive signals including
various types of information or data which are transmitted or
received through a wired interface or wireless interface. The
transceiver 1113, 1213 includes a receiver to receive signals from
an external device and transmit signals to an external device. The
transceiver 1113, 1213 can up-convert OFDM baseband signals to a
carrier frequency under the control of the processor 1111, 1211 and
transmit the up-converted OFDM signals at the carrier frequency.
The transceiver 1113, 1213 can include an (analog) oscillator, and
up-convert the OFDM baseband signals to a carrier frequency by the
oscillator. The transceiver 1113, 1213 may receive OFDM signals at
a carrier frequency and down-convert the OFDM signals into OFDM
baseband signals, under the control of the transceiver 1111, 1211.
The transceiver 1113, 1213 may down-convert the OFDM signals with
the carrier frequency into the OFDM baseband signals by the
oscillator.
[0330] In a wireless communication device such as a UE or BS, an
antenna facilitates the transmission and reception of radio signals
(i.e. wireless signals). In the wireless communication device, the
transceiver 1113, 1213 transmits and/or receives a wireless signal
such as a radio frequency (RF) signal. For a communication device
which is a wireless communication device (e.g. BS or UE), the
transceiver 1113, 1213 may be referred to as a radio frequency (RF)
unit. In some implementations, the transceiver 1113, 1213 may
forward and convert baseband signals provided by the processor
1111, 1211 connected thereto into radio signals with a radio
frequency. In the wireless communication device, the transceiver
1113, 1213 may transmit or receive radio signals containing PDUs,
SDUs, messages or information according to functions, procedures,
and/or methods disclosed in the present disclosure via a radio
interface (e.g. time/frequency resources). In some implementations
of the present disclosure, upon receiving radio signals with a
radio frequency from another communication device, the transceiver
1113, 1213 may forward and convert the radio signals to baseband
signals for processing by the processor 1111, 1211. The radio
frequency may be referred to as a carrier frequency. In a UE, the
processed signals may be processed according to various techniques,
such as being transformed into audible or readable information to
be output via a speaker of the UE.
[0331] In some scenarios of the present disclosure, functions,
procedures, and/or methods disclosed in the present disclosure may
be implemented by a processing device. The processing device may be
a system on chip (SoC). The processing device may include the
processor 1111, 1211 and the memory 1112, 1212, and may be mounted
on, installed on, or connected to the communication device 1100,
1200. The processing device may be configured to perform or control
any one of the methods and/or processes described herein and/or to
cause such methods and/or processes to be performed by a
communication device which the processing device is mounted on,
installed on, or connected to. The memory 1112, 1212 in the
processing device may be configured to store software codes
including instructions that, when executed by the processor 1111,
1211, causes the processor 1111, 1211 to perform some or all of
functions, methods or processes discussed in the present
disclosure. The memory 1112, 1212 in the processing device may
store or buffer information or data generated by the processor of
the processing device or information recovered or obtained by the
processor of the processing device. One or more processes involving
transmission or reception of the information or data may be
performed by the processor 1111, 1211 of the processing device or
under control of the processor 1111, 1211 of the processing device.
For example, a transceiver 1113, 1213 operably connected or coupled
to the processing device may transmit or receive signals containing
the information or data under the control of the processor 1111,
1211 of the processing device.
[0332] In the implementations of the present disclosure, a UE
operates as a transmitting device in uplink (UL) and as a receiving
device in downlink (DL). In the implementations of the present
disclosure, a BS operates as a receiving device in UL and as a
transmitting device in DL. In the present disclosure, a processor,
a transceiver, and a memory, which are included in or mounted on a
UE, are referred to as a UE processor, a UE transceiver, and a UE
memory, respectively, and a processor, a transceiver, and a memory,
which are included in or mounted on a BS, are referred to as BS
processor, a BS transceiver, and a BS memory, respectively.
[0333] The MAC entity according to the implementation(s) of the
present disclosure is implemented by the processor 1111, 1211.
[0334] The processor 1111, 1211 may be configured with the MAC
entity and multiple RLC entities associated with the MAC entity
based on RRC signalling of a BS. One of the multiple RLC entities
may become suspended due to a reason or event related to the one
RLC entity.
[0335] When there is an uplink (UL) grant that the processor 1111,
1211 can use, the processor 1111, 1211 performs an LCP procedure
for the UL grant. As a part of the LCP procedure, the processor
1111, 1211 selects logical channels related to the UL grant, and
allocates resources of the UL grant to the selected logical
channels. In the implementations of the present disclosure, the
processor 1111, 1211 is configured to exclude logical channel(s) of
a suspended RLC entity when performing the LCP procedure. For
example, the processor 1111, 1211 is configured to select the
logical channels related to the UL grant, only from among only
logical channels not related to a suspended radio link control
(RLC) entity among RLC entities configured in the processor 1111,
1211. The processor 1111, 1211 is configured to transmit (or
control the transceiver 1113, 1213 operably connected to the
transceiver to transmit) UL data of the selected logical channels,
to which the resources of the UL grant are allocated, on the UL
grant. The processor 1111, 1211 may allocate the resources of the
UL grant to the selected logical channels in a predefined order of
priority. The processor may perform selecting of the logical
channels related to the UL grant and allocating of the resources of
the UL grant at a medium access control (MAC) entity configured in
the processor.
[0336] In the implementations of the present disclosure, when
calculating data volume for buffer status reporting, the processor
1111, 1211 is configured to exclude logical channel(s) of the
suspended RLC entity. For example, the processor 1111, 1211 may
determine an amount of UL data available for transmission for a
logical channel group (LCG) based on all logical channels of the
LCG except for a logical channel related to the suspended RLC
entity. The processor 1111, 1211 may transmit (or control the
transceiver 1113, 1213 operably connected to the processor 1111,
1211 to transmit) a buffer status report including information on
the amount of UL data available for transmission for the LCG. The
processor 1111, 1211 may receive an UL grant in response to the
buffer status report (via the transceiver 1113, 1213 operably
connected to the processor 1111, 1211) from a BS. The processor
1111, 1211 may perform an LCP procedure for the UL grant as
described above.
[0337] In the implementations of the present disclosure, a logical
channel related to the suspended RLC entity may be a logical
channel related to a suspended radio bearer, a logical channel
related to an RLC entity in which a maximum number of
retransmissions has been reached, a logical channel related to an
RLC entity perform RLC re-establishment, and/or a logical channel
related to a packet data convergence protocol (PDCP) entity
performing PDCP re-establishment.
[0338] As described above, the detailed description of the
preferred implementations of the present disclosure has been given
to enable those skilled in the art to implement and practice the
disclosure. Although the disclosure has been described with
reference to exemplary implementations, those skilled in the art
will appreciate that various modifications and variations can be
made in the present disclosure without departing from the spirit or
scope of the disclosure described in the appended claims.
Accordingly, the disclosure should not be limited to the specific
implementations described herein, but should be accorded the
broadest scope consistent with the principles and novel features
disclosed herein.
[0339] The implementations of the present disclosure are applicable
to a network node (e.g., BS), a UE, or other devices in a wireless
communication system.
* * * * *